A virtual machine is essentially a computer within a computer, implemented in software. Virtual Machine technology, as implemented in Virtual Server, enables customers to run multiple server operating systems concurrently, each in its own isolated software partition, on a single physical server. An application running in a virtual machine behaves the same as an application running on a physical system?it writes information to the file system in the same manner, interacts with the network just as if it were sending packets to a physical NIC. This enables a single hardware server to run multiple operating systems concurrently, each in its own isolated partition. Virtual Server enables customers to multiply server savings.